On Fri, 03 Oct 2003 10:49:40 +0100, Phil Cook <phi### [at] deckingdealscouk> 
wrote:

> On Thu, 2 Oct 2003 15:12:45 -0500, Hughes, B. <omn### [at] charternet> 
> wrote:
>
>>
>> "Phil Cook" <phi### [at] deckingdealscouk> wrote in message
>> news:oprwfbhgleeybzwd@news.povray.org...

<snip me>
>>
>> Looks like a great idea. If you add one more color_map following after 
>> the
>> last #break, and add #else before the color_map, it'll be valid for all
>> times not within the ranges given. That way you get the night sky at 3 
>> a.m.
>> too, which is one of the times I tried.
>
> Hmmm yes I forgot to test it during winter, the values only ran down to 
> -3 million. Writes out 100 times "I must remember to trap errors"
>
>>
>> Sky coloring is always difficult. Right away I thought the purple didn't
>> seem correct for the sunrise/sunset. Although, I think if a layer of 
>> thin
>> clouds or water droplets were present in the air this is the color that
>> might be seen. I'm just guessing, but perhaps a result of the very wide 
>> area
>> it covers it looks out of place. The bright blue above it looks wrong 
>> to me
>> too, too blue without other colors mixed in to offset it. Most times I 
>> think
>> of the real sky colors as muted in some sense, except perhaps the Sun 
>> itself
>> and intensely lit clouds. A bit of imaginative perception can enhance 
>> the
>> coloring. I see a lot of sunrises from my location on a NE facing 
>> hillside,
>> not as many sunsets, and yet I don't believe I could accurately 
>> reproduce it
>> from memory in POV-Ray.
>>
>> Overall I'd say you have too much red mixed into the blue in those color
>> maps.
>
> Thanks, mixing colours is difficult. If I recall my physics correctly 
> the blue is due to atmospheric scattering when passing through all the 
> atmos' then as the sun sets the blue diminishes as green is added to 
> make cyan than the blue goes and the green is added to red to make 
> yellow and then finally the green goes to leave red. Taking the cyan out 
> of the sunsets does produce that magenta colour, but leaving it in seems 
> to produce either banding or unrealistic colours.
>
>>
>> Anyway, I'd suggest the orange range be thinner, closer to the horizon.
>> Here's my attempt at adjusting all the sky colors. Use them if you wish 
>> to,
>> change them some more, whatever. It's only my interpretation of sky
>> coloring.
>>
<snip code>
>
>>
>> Oh, and semicolons aren't required for those declares.  :-)
>
> I know, I know, I tend to stick them on out of habit :)
>
>> I realize all
>> you asked for was an opinion but I love to try sky colors myself.
>>
>> Bob H.
>>
>>
> I was inspired after driving home this week by all the beautiful sunsets.
>
> I must admit I was suprised not to see anything about this on the net or 
> ng's it seemed rather obvious to me to try and tie SunPos and sky_sphere 
> together expecially for doing animations.
>
> The next stage after messing with colours and #range's is some clouds 
> with depth to reflect the sun properly and of course the sun itself 
> which I can't seem to get right,ah well back to dabbling with media.
>
> --
> Phil
>

This may be a backwards step but simplfying the colours seemed to produce 
interesting results:

//start code
global_settings{assumed_gamma 1}

#include "sunpos.inc"

//just to initiate SunPos
#declare lightposition = SunPos(2003, 7, 7, 5, 30, 0, 51.4667, 0.00);

//RERUN SolarPostion but bring in by a factor of 100
#declare newSolarPosition=vrotate(<0,0,10000000>,<-Al,Az,0>);

#macro SunColourMacro()
#switch (newSolarPosition.y)

#range(-9000000, -1250000)
#declare Skycolour =
colour_map{
[0 rgb <0,0,0>]
[1 rgb <0,0,0>]}
#break

#range(-1250000, 0)
#declare Skycolour =
colour_map{
[0 rgb <1,0,0>]
[0.7 rgb <0,0,0>]}
#break

#range(0, 1250000)
#declare Skycolour =
colour_map{
[0.5 rgb <1,0.25,0>]
[0.55 rgb <1,0.5,0>]
[0.8 rgb <0,0,0>]}
#break

#range(1250000, 2500000)
#declare Skycolour =
colour_map{
[0.4 rgb <1,0.5,0>]
[0.55 rgb <1,1,0.5>]
[0.8 rgb <0.5,0.5,1>]}
#break

#range(2500000, 5000000)
#declare Skycolour =
colour_map{
[0 rgb <0.5,1,1>]
[1 rgb <0.5,0.5,1>]}
#break

#range(5000000, 9000000)
#declare Skycolour =
colour_map{
[0 rgb <0.5,0.5,1>]
[1 rgb <0,0.5,1>]}
#break

#else

#declare Skycolour =
colour_map{
[0 rgb <0.5,0.5,1>]
[1 rgb <0,0.5,1>]}
#break
#end
#end


//sky
#declare MySkySphere=
sky_sphere{
SunColourMacro()
pigment{
gradient y
colour_map{
Skycolour}
scale 2 translate -1}};

sky_sphere{MySkySphere}


//clouds
plane{<0,1,0>,1 texture{
pigment{bozo warp{turbulence 0.4 octaves 6  omega 0.7 lambda 2}
colour_map{
[0.0 rgb <0.95, 0.95, 0.95>]
[0.1 rgb <0.85, 0.85, 0.85>]
[0.5 rgbt <1, 1, 1, 1> ]
[1.0 rgbt <1, 1, 1, 1> ]}
rotate<10,20,0>
scale <0.3, 0.4, 0.3>*3 }
finish {ambient 1 diffuse 0}}
scale 1000}

#declare Suncolour = rgb<247/255,255/255,58/255>;

//adjust sphere to match apparent size
#declare MySphere= sphere{<0,0,0> 250000 pigment{colour Suncolour} 
finish{ambient 1 diffuse 0}}

//Use rejigged SolarPosition
light_source {newSolarPosition rgb 1 looks_like {MySphere}}

camera{
location <0,10,-150>
look_at <0,10,10>
}


plane{y,0 texture {pigment{rgb <0.6,0.8,0.196078>*0.9} normal {bumps 0.5 
scale 0.01} finish {ambient 0.45 diffuse 0.55}}}
//end code

This is set to summer times sunrise approx 4.00 I quite like the effect of 
this, not happy around 5.30 yellow seems a bit wishy washy.

Remembered to error trap this time:) Wish I could use some sort of formula 
to alter the colours rather than range jumps though perhaps later.

I think I'll work with these colours for the time being (unless anyone can 
alter these for the better) and start work on a better sun and clouds, 
anyone got any tips?

--
Phil
-- 
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